15.1: Neurones and nervous coordination

Question 1

Two main forms of communication

Answer 1

Nervous system

Hormonal system

Question 2

Nervous system

Answer 2

Uses nerve cells to pass electrical impulses along their length, they stimulate target cells by secreting neurotransmitters directly onto them.

Question 3

Hormonal system

Answer 3

Produces hormones that are transported in the blood plasma to their target cells.

Question 4

Nervous system response characteristics

Answer 4

Responses are short-lived, rapid and restricted to a localised region.

Question 5

Normal system response characteristic

Answer 5

Slower, more widespread, longer-lasting and less specific form of communication. Effect may be permanent and irreversible.

Question 6

Neurones

Answer 6

Are specialised cells adapted to rapidly carrying electrochemical charges called nerve impulses from one part of an organism to another.

Question 7

Cell body of a mammalian motor neurone

Answer 7

Contains all the usual organelles including a nucleus and large amounts of RER.- this is associated with with the production of proteins and neurotransmitters.

Question 8

Dendrons of a mammalian motor neurone

Answer 8

Extensions of the cell body which subdivide into smaller, branched fibres called dendrites, that carry nerve impulses towards the cell body.

Question 9

Axon of a mammalian motor neurone

Answer 9

A single, long fibre that carries nerve impulses away from the cell body.

Question 10

Schwann cells of a mammalian motor neurone

Answer 10

Surround the axon, protecting it and providing electrical insulation, carry out phagocytosis and play role in cell regeneration.

Question 11

A myelin sheath of a mammalian motor neurone

Answer 11

Forms a covering to the axon and is made up of membranes of the Schwann cells, these membrane are rich in myelin. Neurones with a myelin sheath = myelinated neurones.

Question 12

Nodes of ranvier of a mammalian motor neurone

Answer 12

Constrictions between adjacent Schwann cells with no myelin sheath.

Question 13

Three types of neurones

Answer 13

Sensory
Motor
Relay/intermediate

Question 14

Sensory neurones

Answer 14

Transmit nerve impulses from a receptor to an intermediate or motor neurone.
Have one very long dendron.

Question 15

Motor neurones

Answer 15

Transmit nerve impulses from an intermediate or relay neurone to an effector. Have a long axon and many dendrites.

Question 16

Intermediate/Relay neurones

Answer 16

Transmit impulses between neurones. Have numerous short processes.